JP2006129602A - Piezoelectric generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric generator of simple construction that makes it possible to obtain higher power generated than that of piezoelectric generators in the past. <P>SOLUTION: The piezoelectric generator generates power by applying distortional deformation to a piezoelectric ceramic body formed in plate shape. This piezoelectric generator is constructed of the piezoelectric ceramic body, a cushion material that holds the piezoelectric ceramic body in such flexible state that the natural vibration of the piezoelectric ceramic body is less prone to be transmitted to any other structure, and an impact applying means that applies impact to the piezoelectric ceramic body. This impact applying means is formed of steel balls placed at both ends of an elastic supporting member. The piezoelectric ceramic body and the cushion material are supported by an elastic holding body extended in the direction of the piezoelectric ceramic body so that they are in midair and separated from the fixing portion of the elastic supporting member. Vibration from impact application by the steel balls is absorbed by the elastic holding body. With the absorbed force added to the restoring force of the elastic holding body, the piezoelectric ceramic body is returned toward the steel balls. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric power generation apparatus capable of obtaining an output current several tens of times or more than a piezoelectric power generation apparatus using a conventional piezoelectric ceramic element.

  Piezoelectric materials have a variety of applications for transducers between mechanical energy and electrical energy. There are many known materials that exhibit a piezoelectric effect, both inorganic and organic, and materials that are currently in practical use include materials such as ceramic PZT (piezoelectric ceramics).

  Piezoelectric ceramic elements are elements that have a piezoelectric property by applying a DC high voltage to a polycrystal to generate residual polarization, and the basic piezoelectric constant can be changed quite freely depending on the composition. wide. In particular, titanium zirconate-based piezoelectric ceramic elements have a wide composition ratio and a wide selection range of additives and a wide range of applications.

  By the way, the conventional piezoelectric power generation device is one in which a piezoelectric ceramic element plate is bonded to a base such as an acrylic material, and both ends of the substrate are fixed by holders made of a hard material such as metal. Then, a steel ball is dropped from above the ceramic element plate, mechanical impact energy due to collision is applied to the piezoelectric element plate, and flexural vibration is excited in the piezoelectric element plate including the substrate to extract electric energy. It is.

JP 2001-145375 A

  Although the conventional PZT-based piezoelectric ceramic element is expected to be practical, it has a problem that it lacks practicality as a piezoelectric power generation device because of its small amount of power generation. This is because it is indispensable for the piezoelectric power generation apparatus using this type of piezoelectric ceramic element to continue the natural vibration of the piezoelectric ceramic element plate for as long as possible, and how powerful and effective impact force is applied to the piezoelectric element. An important factor is whether or not to provide the ceramic element.

  However, in the conventional piezoelectric power generation apparatus, the natural vibration of the piezoelectric ceramic element plate is not a support structure without mechanical resistance, and the impact force to the piezoelectric ceramic element is also, for example, as shown in Patent Document 1 Still, most of the structures are provided with steel balls. When trying to obtain a sufficient amount of power generation with such a structure using steel balls, the steel balls collide with piezoelectric ceramic elements as many as possible. Had a problem that there was no way.

  In view of this, the applicant of the present patent application in Japanese Patent Application No. 2003-273595 can reliably obtain a power generation amount several tens of times greater than the current output obtained by the piezoelectric power generation device using the conventional steel ball by a single blow. In combination with means that can automatically repeat this blow, for example, as a power source for a mobile phone or a power source for a life-saving buoy etc., it is possible to secure a power generation amount at a practical level for the first time. A possible piezoelectric generator was proposed.

  The proposed piezoelectric power generation apparatus includes a piezoelectric power generation apparatus that generates electric power by applying strain deformation to a piezoelectric ceramic body formed in a plate shape, the piezoelectric ceramic body, and the piezoelectric ceramic body. A cushion material that holds the vibration in a soft state in which vibration is difficult to be transmitted to another structure, and an impacting means that gives an impact to the piezoelectric ceramic body. The impacting means includes a steel ball and the steel ball. A switch member that operates in a striking direction, and the switch member is configured to apply an urging force of an elastic body to the steel ball at the time of an impact operation to the piezoelectric ceramic body by the steel ball. .

  The previously proposed piezoelectric power generation device having the above configuration can obtain a power generation amount of several tens of times or more than the current output obtained by a piezoelectric power generation device using a conventional steel ball by one impact, Since the piezoelectric ceramic body and the cushion material are fixed to the fixed part, a part of the force applied by the steel ball is transmitted to the fixed part without being used for power generation. Had the problem of falling.

  The present invention was devised in view of the current situation, and the object of the present invention is to obtain a larger amount of power generation than the current output obtained by the piezoelectric power generation apparatus previously proposed by the present applicant. A piezoelectric power generator with a simple configuration is to be provided.

  In order to achieve the above object, a piezoelectric power generation apparatus according to the present invention comprises, as described in claim 1, a piezoelectric power generation apparatus that generates power by applying strain deformation to a piezoelectric ceramic body formed in a plate shape. A piezoelectric ceramic body, a cushion material that holds the piezoelectric ceramic body in a soft state in which the natural vibration of the piezoelectric ceramic body is difficult to be transmitted to other structures, and an impact unit that gives an impact to the piezoelectric ceramic body The impacting means is composed of steel balls disposed at both ends of the elastic support member, and the piezoelectric ceramic body and the cushion material are attached to the elastic holding body extending in the piezoelectric ceramic direction. Is held in a hollow state separated from the fixed portion of the steel, and the impact vibration caused by the steel ball is absorbed by the elastic holder, and the absorbed force is added to the restoring force of the elastic holder. The ceramic body is characterized by being configured so as to backward to the steel ball direction.

  Further, the invention according to claim 2 is based on the technical assumption of the piezoelectric power generation device according to claim 1, and a fulcrum body capable of adjusting the vibration period of the elastic holding member between the fixed portion and the elastic holding member. Is arranged to be movable.

  Further, the invention according to claim 3 is based on the technical premise of the piezoelectric power generation device according to claim 1 or 2, wherein the fulcrum body is a piezoelectric ceramic body held by the elastic holder. The space between the steel balls is adjustable.

  As described above, according to the first aspect of the present invention, the piezoelectric ceramic body and the cushion material are held in the hollow state separated from the fixing portion of the elastic support member by the elastic holding body extending in the piezoelectric ceramic direction. The impact vibration caused by the steel ball is absorbed by the elastic holding body, and the piezoelectric ceramic body is moved backward in the steel ball direction with the absorbed force added to the restoring force of the elastic holding body. Therefore, the impact force applied to the piezoelectric ceramic body for the second and subsequent times is the energy stored in the elastic holding body, that is, the energy to the elastic holding body stored by the previous impact force in addition to the impact force by the steel ball. Acts as an elastic restoring force of the elastic holding body, and moves the piezoelectric ceramic body in the direction of the steel ball. The piezoelectric ceramic body has an impact force by the next steel ball and the movement of the piezoelectric ceramic body. The collision force by, it is possible to obtain a large impact force than pressurization impulsive force of the steel ball, the result, it is possible to obtain a larger power generation amount.

  According to the second aspect of the present invention, the fulcrum body capable of adjusting the vibration period of the elastic holding member is movably disposed between the fixed portion and the elastic holding member. And the synchronization of the vibration period can be adjusted, and the power generation efficiency can be further increased.

  Further, according to the invention described in claim 3, since the fulcrum body is configured so that the distance between the piezoelectric ceramic body held by the elastic holding body and the steel ball can be adjusted, the impact force applied to the piezoelectric ceramic body is reduced. It is possible to adjust, and it is possible to effectively prevent breakage due to excessive collision force acting on the piezoelectric ceramic body, and to perform more efficient power generation.

  Hereinafter, the present invention will be described in detail based on Embodiment 1 of the present invention shown in the accompanying drawings.

  FIG. 1 shows a piezoelectric power generation apparatus 50 according to Embodiment 1 of the present invention. The piezoelectric power generation apparatus 50 includes a fixing portion 9 and a piezoelectric ceramic body 10 disposed on the right side of the upper surface 9A of the fixing portion 9. The piezoelectric ceramic body 10 is sandwiched between the cushioning material 3 that holds the piezoelectric ceramic body 10 in a soft state in which the natural vibration of the piezoelectric ceramic body 10 is difficult to be transmitted to other structures, and the upper surface 9A of the fixing portion 9 is sandwiched between the sandwiching bodies 54A and 54B A vertical elastic support 51 formed of a fixed spring material, horizontal elastic supports 52A and 52B fixed to the upper end of the vertical elastic support 51, and both ends of the horizontal elastic supports 52A and 52B The steel balls 53A and 53B, which are hard impactors fixed respectively to the steel ball 53B, are provided with an external force F to the steel ball 53B so that the other steel ball 53A vibrates up and down by a resonance action. Continuously Ri returns, is configured to generate power impact to the piezoelectric ceramic body 10 to beat the piezoelectric ceramic body 10.

That is, the horizontal elastic supports 52A and 52B formed of a metal body such as a rod-shaped stainless steel or a spring material have substantially the same length (l1≈l2) from the upper end of the vertical elastic support 51. And it is fixed by welding.

  Since the structure of the piezoelectric ceramic body 10 itself is the same as that of the piezoelectric ceramic body previously proposed by the applicant, it is not particularly illustrated, but two plate-like pieces of the same material, the same shape, and the same thickness are used. The piezoelectric ceramic elements are ultrathin formed with the polarization polarity of each piezoelectric ceramic element in the same direction, and between the piezoelectric ceramic elements formed of a conductive metal such as phosphor bronze or brass to a thickness of 10 μm to 50 μm. The metal electrode 11 is arranged, and the piezoelectric ceramic element and the metal electrode 11 are joined.

  By setting the metal electrode 11 to the above-mentioned extremely thin thickness, the mechanical resistance due to the metal electrode 11 can be suppressed very slightly, and the joint surface between the two piezoelectric ceramic elements and the metal electrode 11 is centered (a portion that does not expand and contract). ), The damping by the metal electrode 11 can be suppressed as much as possible. In the configuration of the first embodiment, if the piezoelectric ceramic element on one side expands, the piezoelectric ceramic element on the other side contracts, and the electrodes of the output voltage are reversed, so that both piezoelectric ceramic elements are connected in parallel. The generated power generation configuration is obtained.

  Further, in the first embodiment, when the flexural vibration is performed, the one piezoelectric ceramic element performs both the expansion and the expansion and contraction, and the power generation is efficiently performed without the polarization being canceled. . The generated electric current as electric energy is taken out using lead wires conductively connected to both piezoelectric ceramic elements and the metal electrode 11.

  In addition, here, a case where two piezoelectric ceramic elements are laminated with the metal electrode 11 interposed therebetween has been described as an example, but each piezoelectric ceramic element itself can have a laminated structure. In this laminated structure, one piezoelectric ceramic element is formed by joining a plurality of piezoelectric ceramic elements (in this case, the polarity of polarization is also in the same direction).

  As described above, when the piezoelectric ceramic element itself has a laminated structure and is joined by, for example, an adhesive having an elastic characteristic, the bending of the piezoelectric ceramic body 10 lacking in material strength is facilitated by this elastic effect. Bending strength can be maintained. In the present invention, the outer shape of the piezoelectric ceramic body 10 is not particularly limited, and an appropriate shape such as a circle, an ellipse, a triangle, a quadrangle, or a polygon can be used according to the implementation. .

  The cushion material 3 used in the first embodiment is made of a synthetic resin material, a rubber material, or a soft material in which these are made into a sponge shape. The reason why the cushioning material 3 is used and the piezoelectric ceramic body 10 is fixed to the central part or both ends of the cushioning material 3 by using an adhesive is that the vibration of the piezoelectric ceramic body 10 is not attenuated. is there. When the piezoelectric ceramic body 10 vibrates, the member that supports the piezoelectric ceramic body 10 becomes a factor that attenuates the vibration of the piezoelectric ceramic body 10, and in order to remove this damping factor, the piezoelectric ceramic body is made as much as possible by using the cushion material 3. 10 is left free.

  As in the present invention, the distortion of the piezoelectric ceramic body 10 becomes a natural vibration of the piezoelectric ceramic itself and continues for a while, but a part of this natural vibration energy is transferred to the fixed portion 9 in the conventional structure. As described above, the power generation efficiency decreases because it is absorbed and cannot be extracted as electric energy.

For this reason, in the first embodiment, the piezoelectric ceramic body 10 and the cushion material 3 are connected to the holding body 54A on the free end side of the elastic holding body 60 formed of a spring material extending in the horizontal direction. And is held in a hollow state with a height dimension h from the fixed portion 9 of the vertical elastic support member 51. Of course, the piezoelectric ceramic body 10 held by the elastic holding body 60 is positioned directly below the steel ball 53A and is held with a required clearance C.

In the first embodiment, a part of the impact force that has not been converted into the electrical energy of the impact force by the steel ball 53A is absorbed and stored in the elastic holding body 60, and the absorbed and stored force After the elastic holding body 60 is bent and deformed, the piezoelectric ceramic body 10 held by the elastic holding body 60 formed of a spring material is moved back in the direction of the steel ball 53A as a restoring force. It is configured.

In the first embodiment, the fulcrum body 70 capable of adjusting the vibration period of the elastic holding member 60 is movably disposed between the fixed portion 9 and the elastic holding body 60.

The fulcrum body 70 is disposed so as to be movable in the horizontal direction, and by adjusting the length l3 from the contact point (line) between the elastic holding body 60 and the top A to the sandwiching body 54A of the elastic holding body 60. The vibration period from the fulcrum A to the free end can be varied, and it becomes easy to synchronize with the vibration period of the steel ball 53A, and the power generation efficiency can be further increased.

Further, in the first embodiment, the fulcrum body 70 adjusts the distance C between the piezoelectric ceramic body 10 held by the elastic holding body 60 and the steel ball 53A. The mechanism can be moved up and down, and by adjusting the height dimension h between the fixed portion 9 and the fulcrum A, it is possible to adjust the collision force applied to the piezoelectric ceramic body 10 by changing the distance C dimension. In addition, it is possible to effectively prevent breakage due to excessive collision force acting on the piezoelectric ceramic body 10 and to perform more efficient power generation.

  In the first embodiment, the case where the piezoelectric ceramic body 10 has a so-called parallel structure has been described as an example. However, the present invention is not limited to this, and the applicant previously proposed. Of course, the so-called series structure described in Patent Document 1 or a piezoelectric ceramic body having a conventional known structure can be used. However, the highest power generation efficiency is the piezoelectric according to the first embodiment. This is the structure of the ceramic body 10.

  Here, the steel balls 53A and 53B shown in FIG. 1 are formed of 0.9 g of steel balls, the length of l1 and l2 is 120 mm, the cushion material 3 is formed of sponge, and the elastic holding body 60 The length 13 of the elastic holding body 60 and the contact point (line) between the top A and the holding body 54A of the elastic holding body 60 is set to 14 mm, and the interval C is adjusted to 0.5 mm. The amount of power generated by the piezoelectric power generator 1 when the vibration dimension D (see FIG. 1) of the steel ball 53B was set to 10 mm was measured with the measuring device shown in FIG.

  The power generation amount obtained with the power generation device previously proposed by the applicant set to the same conditions was about 3.6 V, whereas the power generation amount obtained with the piezoelectric power generation device 1 of the first embodiment is The voltage was about 4.9V. Compared to the previous power generation device, it was improved by 136%.

In the first embodiment, the case where the horizontal elastic supports 52A and 52B and the vertical elastic support 51 are connected by welding has been described as an example. However, the present invention is not limited to this. Instead, they can be integrally connected by known means such as screwing, caulking, using a strong adhesive, or soldering.

  Since the piezoelectric power generation device according to the present invention is configured as described above, it is possible to obtain a power generation amount larger than the power generation amount obtained by the piezoelectric power generation device previously proposed by the present applicant. It can be applied as a power source for a mobile phone or a power source for a life buoy or the like.

1 is a perspective view showing a schematic configuration of a piezoelectric power generation device according to Embodiment 1 of the present invention. It is explanatory drawing which shows schematic structure of the measuring apparatus which measures the electric power generation amount by the same piezoelectric generator.

Explanation of symbols

A fulcrum C interval (clearance)
h Dimension of distance between piezoelectric ceramic body and steel ball l3 Length dimension from contact point (line) of elastic holding body and top part to holding body of elastic holding body 1 Piezoelectric generator 3 Cushion material 9 Fixing part 9A Upper surface of fixing part DESCRIPTION OF SYMBOLS 10 Piezoelectric ceramic body 52A, 52B Horizontal elastic member 53A, 53B Steel ball 60 Elastic holding body 70 Support point body

Claims (3)

  A piezoelectric power generation device that generates electric power by applying strain deformation to a piezoelectric ceramic body formed in a plate shape, the piezoelectric ceramic body, and the piezoelectric ceramic body transmits the natural vibration of the piezoelectric ceramic body to another structure. The cushioning material that is held in a soft and difficult state and an impacting means that gives an impact to the piezoelectric ceramic body, and the impacting means are composed of steel balls disposed at both ends of the elastic support member. The piezoelectric ceramic body and the cushion material are held in a hollow state spaced apart from the fixing portion of the elastic support member by the elastic holding body extending in the piezoelectric ceramic direction, and the impact vibration caused by the steel ball is absorbed by the elastic holding body. And the piezoelectric ceramic body is configured to move back in the direction of the steel ball in a state where the absorbed force is added to the restoring force of the elastic holding body. Location.   The piezoelectric power generator according to claim 1, wherein a fulcrum body capable of adjusting a vibration period of the elastic holding member is movably disposed between the fixed portion and the elastic holding member.   3. The piezoelectric power generation according to claim 1, wherein the fulcrum body is configured to be capable of adjusting a distance between the piezoelectric ceramic body held by the elastic holding body and the steel ball. apparatus.

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